Materials which can provide aromas with sweet woody, citrusy, vetiver, musky, woody/peppery, woody/leathery, hay and green nuances and/or woody fragrance notes are known in the art of perfumery. Natural materials which provide such fragrances and contribute desired nuances to perfumery compositions, such as natural vetiver oil, are frequently difficult to obtain and/or are high in cost or vary in quality from one batch to another and/or are generally subject to the usual variations of natural products.
There is accordingly a continuing effort to find synthetic materials which will replace the essential fragrance notes provided by natural essential oils or compositions thereof having a vetiver aroma. Unfortunately, many of these synthetic materials either have the desired nuances only to a relatively small degree or else contribute undesirable or unwanted odor to the composition. The search for materials which can provide a more refined vetiver fragrance has been difficult and relatively costly in the areas of both natural products and synthetic products.
Acetonaphthones, particularly octahydro acetonaphthone, are known in perfumery particularly for providing amber or fruity amber fragrance notes which do not discolor with age. Thus, U.S. Pat. No. 3,911,018, issued on Oct. 7, 1975, covers an isomer of octahydrotetramethyl acetonaphthone having the structure: ##STR2## wherein the dashed lines represent methyl groups "cis" to one another.
U.S. Pat. No. 3,911,018 also covers processes for producing isomer mixtures of octahydro-2', 3', 8', 8'-tetramethyl-(2' or 3')-acetonaphthone having the generic formula: ##STR3## wherein one of the wavy lines is a carbon-carbon double bond and the other of the wavy lines represent carbon-carbon single bonds. The mixtures produced by the processes of U.S. Pat. No. 3,911,018 contain from 70 mole percent up to 99 mole percent of compounds having the generic structure: ##STR4## Such a generic structure includes individual compounds having an acetyl group at the 2' position, compounds having an acetyl group at the 3' position and mixtures of such compounds. The generic structures set forth above also include geometric isomers wherein the acetyl group is cis to the methyl group on the carbon atom adjacent to that bonded to the acetyl moiety and where the acetyl group is "trans" to the methyl group on the carbon atom adjacent to that bonded to the acetyl moiety. Furthermore, the products of U.S. Pat. No. 3,911,018 are indicated to be produced by means of a two-step reaction:
1. Reacting myrcene with 3-methyl-3-penten-2-one either:
a. in the presence of a Lewis acid at temperatures in the range of from 0.degree. up to 50.degree. C thereby producing a mixture of geometric isomers which are Diels-Alder adducts which are alkenyl acetyl dimethyl substituted cyclohexenes represented by the structure: ##STR5## or: b. reacting myrcene with 3-methyl-3-penten-2-one without using a catalyst at temperatures in the range of 120.degree. C up to 180.degree. C forming a mixture of isomers (including geometric isomers) of alkenyl acetyl dimethyl substituted cyclohexenes having the generic structure: ##STR6## PA0 1. Diels-Alder Reaction to form Diels-Adler adducts followed by PA0 2. Cyclization of the Diels-Alder adducts is disclosed in detail by Ohloff Ann. 606,100 (1957).
2. Cyclizing the resulting substituted cyclohexenes (Diels-Alder adducts) by means of heating same in the presence of phosphoric acid or dilute sulfuric acid (50-80%) or boron trifluoride or complexes thereof, e.g., boron trifluoride etherate.
Kagi, et al, Journal of the Society of Cosmetic Chemists, (Great Britain), 1973, pages 1-14, "Catalyzed Diels-Alder Reactions in the Synthesis of Perfumery Materials", discloses a synthesis of one of the isomers capable of being produced by the processes of the invention, which isomer has the structure: ##STR7## by means of reacting myrcene and 3-bromo-4-methylpent-3-ene-2-one to give the bromo adduct having the structure: ##STR8## and then dehydrobrominating the said bromo adduct to give the dienone. Kagi, et al, reports that this particular isomer has "a very powerful, musk-ambergris odour" on page 10. The novel isomer as well as the mixture of isomers produced by the instant invention have properties which are advantageous and unexpected with respect to the particular isomer of Kagi, et al.
In addition, British Pat. No. 896,039 entitled "Method of Producing Derivatives of the 1,1-Dimethyl-octahydronaphthalene Series" discloses the generic process: ##STR9## wherein R.sub.2, R.sub.3 and R.sub.4 are disclosed to be the same or different and hydrogen or alkyl and R.sub.1 is disclosed to be hydroxy, alkyl or alkoxy. The British patent discloses this process to be useful for producing products "resembling the well known class of violet perfumes". Indeed, Example 5 of the British patent alleges that the compound 1,1,6,6-Tetramethyl-7-ketomethyl-Octalin produced by (1) reacting myrcene and mesityl oxide thermally followed by (2) subsequent cyclization, has a pleasant "woody ambergris smell". However, a repetition of the teachings of this British patent gives rise to the following results: ##STR10##